Sound reproducing apparatus



Oct. 12, 1937. E. w. REYNOLIQDS 2,095,238

SOUND REPRODUC ING APPARATUS Filed July 26, 1935 S bUND REPItODUCING APPARATUS 7 Ellwood W; Reynolds, Lansdowne, Pa., assignor to Radio Corporation of'America, a corporation'of Delaware Application July. 26, 1935, Serial No. 33,261

9 Claims; "(01. 179-1003) .This invention relates to sound reproducing apparatus of the'photographic'type, andmore particularly to means in such apparatus for preventing distortion ''of thereproduced sound resulting from microphonics. v I In the construction of sound reproducing machines wherein sound is reproduced from a photographic record by electro-optical means, it has been proposed. to individually mechanically insu late such 'microphonic parts as exciter lamps, photoelectric cells, transformers, head amplifiers,

etc. against mechanical vibration. It has been found, however; that where the. vibration insulation of these parts ismade sufficiently good to eliminate microphonics, they will not stay mechanically aligned with each other. a This is particularly true in the case of exciterlamps which are subjected to considerablemanual force when exchanged.

' The primary object ofmy invention is toipror vide improved sound reproducing apparatus of the foregoing type which will not be subject to the difficulties encountered in prior art machines from microphonics. a

I More specifically, it is an objectof my invention to provide improvedsound reproducing apparatus wherein-distortion normally resulting from microphonics of the sound translating parts caused by the gearing, intermittent mechanism, film reels, etc., of the apparatus will be eliminated. v

A further object of my invention is to provide an improved mounting for the sound translating parts of sound reproducing'apparatus employing photographic records whereby such parts will always remain in desired mechanical alignment, once securely arranged therein.

Another object of my invention is to provide an improved mounting as aforesaid which'is inexpensive of manufacture and highly efficient in use.

In accordance with my invention, I combine all of the microphonic and necessary film handling parts on one supporting structure or plateand vibration insulate the plate from the remainder of the machine. All of the parts on the plate are then rigid with respect to each other and therefore in mechanical alignment at all times.

Figure supporting plate 'I. thereon a socket 9 for receiving a filamentary or V phonic noises.

the insulation maybe concentrated in "small, neat, inconspicuous and inexpensive cushioning members for supporting the entire, heavy assembly', With this construction, I have found that microphonics are practically entirely eliminated even when amplifiers are operated at high gain.

The novel features that I considercharrcteristic of my inventionare set forth with particularity in the appended claims. The invention itself, howver, both as 'to its organization and method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment, when read in connection with the accompanying drawing, in which Figure 1 is a front elevation of a sound reproducing machine constructed in accordance with my invention, and

2 isa plan'view thereof, partly insection. r 0

Referring more specifically to the drawing,

wherein similar reference numerals indicate corresponding parts throughout, thereis shown a casing I providedwith inwardly-extending, upstanding portions or standards 3 and 5 which carry a The plate 1 has mounted other suitable exciter lamp ii, an optical system I 3 for projecting a fine line of light from the lamp ll onto a film IS, a socket I! for a photoelectric cell [9, and a lens holder 2| for a lens 23 which directs the light beam, after having traversed the film I5, onto the photoelectric cell I9.

The film I5 is drawn past the scanning light by a constant speed sprocket 25 while trained around a sound drum 2! with which it is held firmly engaged by an idler'29. The drum 21 is fixed to one end of a shaft 3| which is journalled in a casting 33 cast integral with the plate 1 and to the other end of which is fixed a suitable fiywheel or other inertia member 35 in order to insure uniformity of speed of the film past the scanning light. l

OF ICE In apparatus heretofore in use, the plate 1 was rigidly secured to the standards 3 and 5, and the exciter lamp socket 9, the photoelectric cell socket ll, the optical system l3 and the lens mounting 2| were each, or at least some of them, mounted on the plate I by resilient means to prevent mechanical vibrations from reaching and disturbing them and thereby produce micro- I have found, however, that much better results can be obtained by mounting these parts rigidly on the plate 1 and by insulating the plate I from the standards 3 and 5 against vibration. To this end, I provide a plurality of rubber, felt, or similar mounting pads or cushions 31 between the plate 1 and the standards 3 and 5, with at least one pad placed adjacent each corner of the plate 1. Thus, mechanical vibrations produced in the system as in the driving mechanism mounted externally of the plate I, are effectively absorbed by the pads 31 and their transmission to the plate I and the parts supported thereon is prevented.

Although I have shown and described but one specific embodiment of my invention, I am fully aware that many modifications thereof are possible. For example, instead of mounting the plate 1 on the upstanding standards 3 and 5, it may be mounted on the base of the casing l or upon a base plate therein through cushioning members. Also, in place of the pads 31, strips of. cushioning material may be used. It is also within the scope of my invention to mount upon the plate 1 an amplifier, transformer, or any other parts necessary to reproduce the sound, as well as to leave off any of the parts shown in the drawing. If desired, the individual parts, such as the exciter lamp socket, the optical system, the photoelectric cell socket, etc. may each or any of them be individually vibration insulated from the plate I, as heretofore, and the plate I vibration insulated from its support as well. All these, and many other changes and modifications of like nature, are contemplated within the scope of my invention. Moreover, although I have shown and described my invention as applied to sound reproducing apparatus, it will, no doubt, be apparent to those skilled in the art that it is equally applicable to sound recording apparatus as well. I desire, therefore, that my invention shall not be limited except insofar as is necessitated by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. In phonographic apparatus of the type employing driving means subject to slight mechanical vibrations and electro-optical means for translating acoustical vibrations onto or from a record, a casing, a supporting member in said casing carrying at least part of the translating mechanism but none of said driving means, and

means for vibration insulating said supporting member from said casing.

2. In phonographic apparatus of the type employing driving means subject to slight mechanical vibrations and electro-optical means for translating acoustical vibrations onto or from a record, a casing, a supporting member in said casing carrying the translating mechanism but none of said driving means, and resilient means interposed between said casing and said supporting member for vibration insulating said member from said casing.

3. The invention set forth in claim 2 characterized in that the translating mechanism comprises a plurality of cooperative parts all rigidly fixed to said supporting member in predetermined relation.

4. The invention set forth in claim 2 characterized in that said translating mechanism includes an exciter lamp mounting and a photoelectric cell mounting, said mountings being rigidly fixed to the supporting member in predetermined relation.

5. In phonographic apparatus of the type employing driving means subject toslight mechanical vibrations and electro-optical means for translating acoustical vibrations onto or from a record, a casing, a pair of standards on said casing, a supporting plate carrying the translating mechanism but none of said driving means, and resilient meansinterposed between said standards and said supporting plate for vibration insulating said plate from said casing.

6. The invention set forth in claim 5 wherein said resilient means comprises a plurality of individual pads.

'7. The invention set forth in claim 5 wherein said resilient means comprises a plurality of rubber pads.

8. The invention set forth in claim 5 wherein said resilient means comprises a plurality of rubber pads, with at least one pad adjacent each corner of said supporting plate.

9. The invention set forth in claim 5 wherein said resilient means comprises a plurality of strips of rubber.

ELLWOOD W. REYNOLDS. 

